package com.qying.other;

import java.util.Arrays;

public class FloydAlgorithm {

    public static void main(String[] args) {
        char[] vertex = {'A','B','C','D','E','F','G'};
        int[][] matrix = new int[vertex.length][vertex.length];

        final int N = 65535;
        matrix[0] = new int[]{N,5,7,N,N,N,2};
        matrix[1] = new int[]{5,N,N,9,N,N,3};
        matrix[2] = new int[]{7,N,N,N,8,N,N};
        matrix[3] = new int[]{N,9,N,N,N,4,N};
        matrix[4] = new int[]{N,N,8,N,N,5,4};
        matrix[5] = new int[]{N,N,N,4,5,N,6};
        matrix[6] = new int[]{2,3,N,N,4,6,2};

        Graph graph = new Graph(vertex.length,matrix,vertex);
        graph.floyd();
        graph.show();
    }
}

class Graph{
    private char[] vertex;
    private int[][] dis;
    private int[][] pre;


    public Graph(int length, int[][] matrix, char[] vertex) {
        this.vertex = vertex;
        this.dis = matrix;
        this.pre = new int[length][length];

        for (int i=0;i<length; i++){
            Arrays.fill(pre[i],i);
        }
    }

    public void show(){
        char[] vertex = {'A','B','C','D','E','F','G'};

        for (int k =0; k< dis.length;k++){
            for (int i = 0; i <dis.length ; i ++){
                System.out.print(vertex[pre[k][i]] + "    ");
            }
            System.out.println();

            for (int i = 0; i <dis.length; i++){
                System.out.println("("+vertex[k]+"到"+vertex[i]+"的最短路径是"+dis[k][i]+")");
            }

            System.out.println();
            System.out.println();
        }
    }

    public void floyd(){
        int len = 0;
        for (int k =0 ;k < dis.length;k++){
            for (int i =0; i< dis.length; i++){
                for (int j =0;j<dis.length;j++){
                    len = dis[i][k] + dis[k][j];
                    if (len < dis[i][j]){
                        dis[i][j] = len;
                        pre[i][j] = pre[k][j];
                    }
                }
            }
        }
    }
}
